Fractionating method



Jan. 10, 1933. .1. PRIMROSE FRACTIONATING METHOD 2 Sheets-Sheet FiledApril 8, 1927 Jan. 10, 1933. .1. PRIMROSE FRACTIONATING METHOD FiledApril 8. 1927 2 Sheets-Sheet 2 INVENIORS f0H/V PR/MFOJE W TTORNEYPatented Jan. 10, 1933 UNIITE'D STATES PATENT OFFICE JOHN PRIMROSE, OFRICHMOND, NEW YORK, ASSIGNOR T0 FOSTER WHEELER CORPORA- TION, OF NEW.YORK, N. Y., A CORPORATION OF NEW YORK I FRAGTIONATING METHODApplication filed April 8,

The general object of the present invention is to provide an improvedmethod of fractionally distilling stock oil such as crude petroleum orthe relatively heavy residues of other mineral oil distillationprocesses, to produce fractions with small differences in boiling pointdifferentials between the fractions buthaving certain clearly defineddifferences in physical characteristics. The invention was primarilydevised and is especially adapted for the production from stock oil ofthe character specified of lubricating oil fractions with smalloverlapping from the viscosity standpoint of the fractions.

The invention is characterized primarily by the fact that the stock oilis heated to the maximum temperature required in the process with suchuniformity and rapidity as to substantially avoid the cracking whichwould occur if the oil were heated to the same temperature at the slowerrate of which oil is normally heated to such temperatures in ordinaryoil refining operations. In practice I thus heat the oil in a tubularoil heater which may be the same as, or similar in type to ordinarytubular oil heaters, but for the purposes of the present invention thenumber of, or the manner of connecting the tubes, or the rate at whichthe oil is passed through the tubes is such that the required time foreach particle of the oil to pass through the heater tubes issubstantially smaller than has heretofore been the practice in heatingoil in a tubular oil heater for oil refining purposes.

After being thus heated the oil is treated in a fractionating tower inwhich the oil, and the condensates formed in the upper portion of thetower from vapors liberated in the lower portion of the tower aresubjected to an intimate contact with the steam and va-v pors passing upthrough the tower from which the desired fractions are withdrawn at1927. Serial No. 181,973.

asphaltic base petroleums, but also from parbulk. Furthermore, theapparatus required is comparatively simple and inexpensive inconstruction, and is characterized by relatively low maintenance andoperation costs.

The various features of novelty which characterize my invention arepointed out with particularity in the claims annexed to and forming apart of this specification. For a better understanding of the invention,however, and the advantages possessed by it, reference should be had tothe accompanying drawings and descriptive matter in which I haveillustrated and described a preferred embodiment of the invention.

Of the drawings:

Fig. 1 is a dlagrammatic representation of apparatus for use in carryingout the method;

Fig. 2 is a section on the line 22 of Fig. 1;

Fig. 3 is a sectional elevation of. an oil heater shown in Fig. 1;

- Fig. 4 is a partial sectional plan;

Fig. 5 is a section on the line '5-5 of Fig. 4; and

Fig. 6 is a partial section on the line 66 of Fig. 5.

The particular form of apparatus illus-v trated inthe drawings for usein carrying out the method comprises a tubular oil heater A receivingoil from a supply pipe B and'delivering oil and oil vapors to afractionating tower D through an outlet pipe C.

The oil heater A may be of various types provided it is capable ofoperation in such manner as to progressively heat the oil to the maximumtemperature required with a rate of fi-ow of oil through the tubes ofthe heater which is sufliciently rapid to avoid appreciable cracking ofthe oil. As shown, the heater A comprises a combustion chamber A inwhich fluid fuel supplied by one or more burner j pipe B is connected toone or more of the tubes A in the bottom row of tubes through an inletheader A". The oil passes successively through tubes A at successivelyhigher levels until it reaches an outlet pipe or pipes A through whichthe oil is passed to tubes A lining the roof of the heater. The tubes Aare heated mainly by the absorption of radiant heat. The oil passes fromthe tubes A through the outlet connection A to the delivery pipe C.

The heater A, as shown, is of the well known Foster heater type now inextensive commercial use. As is ordinarily the case in heaters of thistype, the tubes N and A may be so connected that the oil may passsuccessively through all or a substantial portion of the tubes A in anylower row before passing to the tubes A in the row immediately above,and may pass in series through all or a substantial portion of the tubesA, though instead of a single undivided oil flow path including all ofthe tubes A and A connected in series, the tubes may be connected todivide the entire path of flow, or some portions thereof into separatedparts in which the flow is in parallel. In any event, the heateremployed differs from tubular oil heaters heretofore used by such adecrease in the length of the path of oil flow, and/or such an increasein the velocity of the oil, that the time required for any particularparticle of oil to travel from the inlet header A to the outlet header Ais but a relatively small fraction of the time required for the oil topass from the inlet to the outlet of tubular oil heaters employed inordinary oil refining operations.

For example, in treating crude as haltic base petroleum for theproduction lubricating' oils in accordance with the present invention, Ihave obtained excellent results by heating the oil from an initialtemperature of 300 degrees F. to a final temperautre of 775 degrees F.in a heater of the type shown in which the tubes connected in seriesbetween the oil inlet and the oil outlet provided a path of oil flow1200 feet in length, and through which the time of travel of anyparticle of oil was about to 12 seconds. It will be understood, ofcourse, that the figures just mentioned are given by way of illustrativedescription and may be widely departed from while stillproceeding inaccordance with the invention herein disclosed and claimed.

Advantageously, though not necessarily, the steam employed in thefractioning power I) is superheated by passing it through a convectionsuperheater S located in the chamber A between upper and lower banks oftubes .A. at a suitable elevation. The steam to be superheated is passedto the superheater S through a steam supply pipe S and the superheatedsteam is passed from the superheater through a pipe S to inlets Sopening to the tower D at suitable levels.

The fractionating tower D, comprises a suitably elongated verticallydisposed shell, with provisions for effecting intimate contact thereinbetween ascending oil vapors and steam and descending liquid, and forobtaining a desirable reflux action at the top of the tower, and forinjecting steam into, and for withdrawing condensate fractions from thetower at suitably different levels.

As shown, the tower D, which constitutes a fractionating zone, is of thetype disclosed and claimed in my copending application filed jointlywith Harry R. Swanson under Serial No. 106,866, May 5, 1926. The meansfor effecting the desired liquid and vapor contact comprise amultiplicity of superposed bubble trays E, which may be of any usual andsuitable construction. As shown, the trays E are formed with a pluralityof elongated side by side gas ports E each surrounded by a marginalflange at the upper side of the tray, and extending into a correspondingbell E Each tray E is provided with liquid draining provisions. Asshown, every alternate tray E is provided with a simple drain pipeextension E located at one side of the shell and extending downward intoproximity with the subjacent tray E so that the lower end of the drainpipe may be sealed by the liquid normally carried by the subjacent tray.Some or all of the intermediate trays E, are provided with two side byside short drain pipes E (see Figs. 4 and 5), each dipping into acorresponding receptacle I. Each receptacle I is formed with a weirnotch or orifice I from which-liquid overflows.

'The liquid overflowing from the two receptacles I pertaining to thesame tray E may fall wholly or partly onto the subjacent tray E, or maybe received in part or in whole in an adjustable trough-like member Kemployed to pass liquid into a correspondmg condensate outlet box H.While in any particular installation, operating under any particularcondition of use, liquid is withdrawn from the tower through outletboxes H associated with a small portion only of the total number oftrays E, I consider it ordinarily desirable to provide the tower with anoutlet box H associated with every other one of the trays E, so that thelevels at which condensate fractions may be withdrawn from the towerthrough the outlet boxes H may be readily may be connected to an outletpipe H accordingly as condensate is, or is not, to be withdrawn from thetower through that box H. -As shown, the trough K associated with eachbox H extends through the corresponding port D and is movable toward andaway from the axis of the tower D on guides H carried by thecorresponding box H. The inner end of the trough K terminates in anuprising plate-like portion K, having notched side edges which projectinto the weir notches I of the corresponding receptacles I. When saidportion K is intermediate the ends of the corresponding weir notches itin effect divides each of the latter into two Weir notches one of whichdischarges into the trough K, and the other of which discharges onto thesubjacent tray E, and the relative amounts of liquid so discharged bythe two portions of each Weir notch may be precisely controlled andadjusted by moving the trough K toward and away from the axis of thetower D. This adjustment of the trough is provided for in theconstruction shown by means of a shaft extending through and rotatablymounted in the outer wall of each box H and having a threaded portion Kin threaded engagement with a lug K of the corresponding trough memberK, and carrying an external hand wheel K by which the shaft is rotated.The position of each trough K may be indicated by an arm K in threadedengagement with an externally threaded portion K of the adjusting shaft,andarranged to move along a scale member EK secured to I thecorresponding box H.

The condensate fraction withdrawn from the tower D at any level throughthe corresponding outlet box H might pass directly from the latter tosuitable cooling and collect ng or storage means, but as shown, eachcondensate fraction withdrawn from the tower through an outlet box H isreturned to the tower at a level somewhat below the level from which thefraction is withdrawn.

To th s end, the outlet pipe H associated with each box H through whichcondensate is withdrawn, forms abypass about a corresponding portion ofthe tower which we call a clean-up section. e

As shown, there are four of these clean-up sections L, L L and L Eachclean-up section comprises provisions for collecting and rectifyingcondensate and reflux liquid coming to the section from the bubble traysE above it. As shown each clean-up section comprises means providing aliquid pocket 6, and means for scrubbing or removing low boilingcomponents from the condensate collecting in the pocket 6 with steamsupplied through a corresponding inlet S from the pipe S before theliquid is withdrawn from the pocket through the corre spondingfractional condensate outlet. Associated with the clean-up section L, LL and L are corresponding fractional condensate outlet pipes M, M M andM which conduct from the tower the intermediate fractions of the oilbeing fractionated. As shown, the outer wall of each liquid pocket e isformed by the tower shell, and its inner and bottom walls are formed bya member L which may be described as of inverted funnel shape having atits bottom an outwardly extending flange which extends into contact withand is secured to the tower shell. As shown, the body of each member Lis rectangular in cross section, and so proportoned as to fill centralopenings in two special superposed trays EA and EB. The trays EA and EBdiffer from the trays E hereinbeforedescribed only in the omission ofportions including some but not all of the gas ports E.

The condensate outlet pipes M, M M and M are connected to heatexchangers O, O,

() and 0*, respectively, which are succesg sively traversed by the stockoil passing to and as shown, each outlet pipe comprises a dependingU-shaped portion M for maintaining a l'quid seal at the outlet, from thecorresponding clean-up sections L, L L and L The condensate fractionscooled in the heat exchangers 0, O 0 and 0 pass from the latter throughpipe P, P P and P respectively to suitable purifying and storageapparatus (not shown). Uncon densed oil vapors and steam pass from thetop of the tower D through an outlet D to a heat exchanger 0 through whch the stock oil supplied by the pipe 5 passes to the heat exchangers O,etc. The outlet from the space of the heat exchanger 0 re- .ceivingvapors from the pipe D is connected through coolers T and T to a pipe Twhich conveys the lightest fraction of the oil bengfractionated from thetower to the gasoline purifying and storage apparatus (not shown). Abranch pipe T provides means through which a portion of the condensateformed in the heat exchanger 0 and cooler T may be returned by gravity,or by means of a pump (not shown) to the top of the tower D for refluxpurposes.

. evaporated in descending through the tower,

constituting what will be termed the heaviest fraction of the oil beingfractionated and is withdrawn from the bottom of the tower through anoutlet piue U connected to the inlet of a pump TV through a heatexchanger 0 through which the stock. oil passes from the heat exchanger0 to the inlet of the heater A. Advantageously, a body of liquid isalways maintained in the lower portion of the tower.

' a high grade gasoline through the pipe T tions L, L L and L.

kerosene through the pipe P, gas oil through the pipe P wax distillatehaving a viscosity of Saybolt seconds at 100 F. through the pipe P andlubricating stock oil having a viscosity of 150 Saybolt seconds at 210F. through the pipe P*. It will be apparent, of course to those skilledin the art that the relative amounts and the character of the ultimatefractions withdrawn, may be varied by varying the character of the stockoil employed, the temperature to which it is heated, and the temperatureand amounts of superheated steam supplied to each of the inlets SFurthermore, in addition to the control of the ultimate productsobtained by regulating the factors just referred to, an importantregulation or control of the ultimate fractions recovered can be had byadjusting the by-pass H about each of the clean-up see- This adjustmentmay be made in either or both of two ways. First, by adjusting thetrough K of the outlet box H to which the upper ends of each bypass isconnected so as to vary the relative amounts of the liquid dischargedthrough the corresponding weir notches I which pass to the immediatelysubjacent clean-up section and to the tower below that clean-up section.Secondly, by changing the levels at which either or both ends of eachby-pass is connectedto the tower.

The effect of thus adjusting the by-pass about each clean-up section isto vary the action and operative result of the clean-up section. Themere adjustment axially of the tower of the trough K above, andoperatively associated with each clean-up section, is to increase ordecrease the amount of liquid treated in that section. An increase ordecrease in the amount of the liquid treated in the section, otherthings being equal, tends Advantageously, also the outlet pipes P, P Pand P for conveying the clean-up section is obviously modified.Similarly by varying the level of the lower end of each upper by-passthe character of the fraction collected in 'and treated in theimmediately subjacent clean-up section is modified. The fraotionatingtower D comprises various novel features of construction and arrangementwhich are not claimed herein but which are claimed in my said priorapplication filed jointly with Harry R. Swanson under Serial N 0.106,866, May 5, 1926. As in the construction described in the priorapplication just referred to, bafile plates or analogous liquid and gasseparating screens X may advantageously be located between the'trays Eat various levels to eliminate entrained liquid from the vapors passingupward through the tower.

While a fractionating tower of the particular construction illustratedand described is especially well adapted for use in practicing thepresent invention, the latter in its broader and more general aspects isindependent of the character of the fractionating tower employed.

While in accordance with the provisions of the statutes, I haveillustrated and described the best form of embodiment of my' inventionnow known to me, it will be apparent to those skilled in the art thatchanges may be made in the form of the apparatus disclosed withoutdeparting from the spirit of my invention as set forth in the appendedclaims and that in some cases certain features of my invention may beused to advantage without a corresponding use of other features.

Having now described my 1nvent1on, what I claim as new and desire tosecure by Letters Patent, is:

1. The method of oil fractions with small overlapping'from the viscositystandpoint, which consists in progressively heating stock oil to thedesired maximum temperature in a tubular oil heater through which theoil is passed with such rapidity as to substantially avoid the crackingwhich would occur if the'oil were heated to the same temperature moreslowly, then subjecting the oil to fractional distillation andcondensation in a fractionating tower in which the oil and thecondensates and reflux producing lubricating I scending liquid aboutsections 0 liquid, if any coming down through the tower are subjected tointimate contact with steam and vapors passing upward through the tower,collecting bodies of condensate within the tower at different levels,separately withdrawing fractions from the tower at the different levelsand regulating the character of the fractions so withdrawn byintroducing the steam separately into a plurality of the bodiescollected and variably fpassing desaid tower containing the collectedbodies.

2. The method of producing lubricating oil fractions with smalloverlapping in viscosity which comprises progressively heating stock oilto the desired maximum temperature in a tubular oil heater through whichthe oil is passed at suflicient velocity to substantially avoidcracking, then passing the oil and the vapor formed during the heatinginto a fractionating tower in which the uprising vapors are subjected tointimate contact with condensates and reflux liquid descending throughthe tower, collecting and maintaining sub stantial bodies of condensateof diflerent boiling ranges at different levels in the tower, scrubbingsaid bodies of condensate withsuperheated steam, separately andcontinuously withdrawing portions of said condensate at said diflerentlevels, and variably passing descending condensate and reflux liquidabout said bodies of condensate.

3. In the art of fractionally distilling hydrocarbon oils, the methodwhich comprises passing vapors of the oil counter-current to and incontact with reflux oil in a fractionating zone, dividing the flow ofliquid oil intermediate the lightest and heaviest frac-' tions intoportions, passing one portion counter-current to steam in contacttherewith in the fractionating zone to remove low boiling components,thereby yielding an intermediate fraction of higher flash point andcontinuing the other portion of the liquid oil counter-current to thevapors in an earlier stage of the fractionating system.

4. In the art of fractionally distilling hydrocarbon oils, the methodwhich comprises passing vapors of the oil counter-current to and incontact with reflux oil in a fractionating zone, dividing'the flow ofliquid oil intermediate the lightest and heaviest fractions intoportions, passing one portion into contact with steam in thefractionating zone to remove low boiling components, thereby yielding anintermediate fraction of higher flash point and continuing the other portion of the liquid oil counter-current to the vapors in an earlier stageof the fractionating system.

5. The method of producing lubricating oil from petroleum containingasphalt which comprises passing the oil partially vaporized into afractionating tower wherein the vapors pass counter-currentto andincontact with descending reflux oil, dividing the downward flow of refluxoil intermediate the lightest and heaviest fractions, passing a portionso divided counter-current to steam in contact therewith in the tower toremove low boiling components therefrom, thereby yielding anintermediate fraction of lubricating oil having high flash point andwithdrawing from the bottom of said system an asphaltic residuum.

' 6. In the art of fractionally distilling hydrocarbon oils, the methodwhich comprises heating oil to produce vaporization thereof, introducingthe oil into a fractionating tower, passing the vapors of the oilcounter-current to and in contact with downflowing liq- ,uid oil,dividing the downward flow of liquid oil in the tower intermediate thelightest and heaviest fractions, collecting a divided portion of liquidoil within the tower, introducing steam into direct contact with theliquid Oll collected .in the tower and passing the steam counter-currentto flow of oil into the body collected, withdrawing the liquid of thecollected body as an intermediate fraction product and by-passing theother divided portion of liquid oil around said collected body downwardto an earlier stage of the fractionating system.

7. In the art of fractionally distilling hydrocarbon oils, the methodwhich comprises heating oil to produce vaporization thereof, introducingthe oil into a fractionating tower, passing the vapors of the oilcounter-current to and in contact with downflowing liquid oil, dividingthe downward flow of liquid oil in the tower intermediate the lightestand heaviest fractions,'collecting a divided portion of liquid oilwithin the tower, scrubbing the body of liquid oil by introducing steamdirectly thereinto to remove low boiling components, withdrawing theliquid of the collected body as an intermediate fraction product andby-passing the other divided portion of liquid oil within the tower,scrubbody downward to an earlier stage of the fractionating system.

8. The method of producing lubricating oil from petroleum whichcomprises heating petroleum to produce vaporization thereof,

liquid oil in the tower intermediate the light- 3 est and heaviestfractions, collecting a divid ed portion of liquid oil within the tower,introducing steam into the tower into direct contact withthe liquid oilcollected, withdrawing the liquid of the collected body as anintermediate fraction product, by-passing the other divided portion ofliquid oil around said collected body downward to an earlier stage ofthe fractionating system and withdrawing from a lower portion of saidStO tower a residual oil heavier than said lubrieating oil.

9. The method of producing lubricating oil from petroleum containingasphalt which comprises heating the petroleum to produce vaporizationthereof, introducing the same into a fractionating tower, passing thevapors of the oil counter-current to and in contact with downflowingliquid oil, dividing the downward flow of liquid oil in the towerintermediate the lightest and heaviest fractions,

collecting a divided portion of liquid oil within the tower, introducingsteam into the tower into direct contact with the liquid oil collected,withdrawing the intermediate fraction lubricating oil of the collectedbody and withdrawing from the bottom of the tower sively decreasingtemperature, dividing the downward flow of condensate at a plurality ofpoints of different temperature in the fractionating path, collectingbodies of condensate so divided of different average boiling point inthe tower and continuing the remainder of each condensate divisiondownward to a higher temperature stage of the fractionating path but oflower temperature than any point of condensate divislon of highertemperature, introducing separate streams of steam into each of thecollected bodies to drive ofl' low boiling point constituents andpassing each of the plurality of streams of introduced steam togetherwith accompanying oil vapor into a lower temperature stage of thefractionating path but of higher temperature than any point ofcondensate division of lower temperature.

11. That improvement in the art of oil fractionation in a fractionatingtower having downfiow of condensed oil over contact surfaces and incontact with upflowing vapors which consists in collecting condensate ata plurality of levels in the tower to obtain fraction products,introducing steam'into a plurality of the bodies collected to remove lowboiling point constituents and introducing the steam and oil vaporscarried thereby into the downflowing liquid and regulating the relativeamounts collected to the remaining downflowing liquid to regulate thecondensing efiect to reduce the percentage of high boiling 'pointconstituents of the collected bodies.

12. The method of producing oil fractions with small overlapping ofviscosity values tively high velocity through a tubular oil heater,introducing the oil so heated into a fractionating tower, pasing thevapors of the oil upwardly in'the tower in contact with downflowingcondensate whereby the vapors have an upflow path of graduallydecreasing temperature in the tower, dividing the downward flow ofcondensate in the tower at a plurality of points of differenttemperature, collecting divided portions of condensate in the tower atlevels below the points of condensate division, introducing separatestreams of steam into a plurality of the collected bodies to drive offlow boiling point constituents, by-passing the condensate vnot collectedat each point of division into the higher temperature 'zone of the towernext below the level of the respective collected bodies and passing eachof the plurality of streams of introduced steam together withaccompanying oil vapor into the lower temperature zone of the tower nextabove the level of the respective collected bodies.

13. The method of producing oil fractions with small overlapping ofviscosity values which comprises heating liquid oil so as to vaporizethe same but to substantially avoid cracking thereof by passing the oilwith a relatively high velocity through a tubular oil heater,introducing the oil so heated into a fractionating tower, passing thevapors of the oil upwardly in the'tower in contact with downflowingcondensate whereby the vapors have an upflow path of graduallydecreasing temperature in the tower, dividing the down- 'ward flow ofcondensate in the tower at a plurality of points of differenttemperature, collecting divided portions of condensate. in the tower atlevels below the points of condensate division, introducing separatestreams of steam into a lurality of the collected bodies to drive 0% lowboiling point constituents, variably by-passing the condensate notcollected at each point of division into the higher temperature zone ofthe tower next below the level of the respective collected bodies andpassing each of the plurality of streams of introduced steam togetherwith accompanying oil vapor into the lower temperature zone of the towernext above the level of the respective collected bodies.

14. The method of fractionally distilling hydrocarbon oils whichcomprises heating the oil to vaporization temperature, introducing theheated oil intov a'fractionating tower, separating-the vaporized andunvaporized portions of the oil in. the tower, passing the vaporizedportion of the oil in a path counter-current to and in contact withreflux oil in the tower, collecting in the tower in the path of flow ofthe vapors but out of contact therewith, reflux oil intermediate thelightest and heaviest fractions of the oil, subjecting the collectedreflux to contact with steam, withdrawing the steamed reflux from thetower, passing the unvaporized portion of the oil counter-current to andin contact with steam and withdrawing the steamed unvaporized portionfrom the tower.

15. The method of fractionally distilling hydrocarbon oils whichcomprises heating the oil to vaporization temperature, intro" ducing theheated oil intoa fractionating tower having a plurality of bubble traystherein, separating the vaporized and unvaporized portions of the oil inthe tower, passing the vaporized portion of the oil in a continuous pathcounter-current to and in contact with reflux oil in the tower,collectin in roduction of oil thereinto and out of contact with thevapors of the oil flowing through the tower, subjecting the collectedreflux to contact with steam,withdrawing the steamed reflux from thetower, passing the unvaporized portion of the oil counter-current to andin contact with steam, commingling the oil vapors evolved by said steamwith the vaporized portion of the oil introduced into the tower andwithdrawing the steamed unvaporized portion from the tower.

16. The method of fractionally distilling hydrocarbon oils whichcomprises heating the oil to vaporization temperature, introducing theheated oil into a fractionating tower, separating the vaporized andunvaporized portions of the oil in the tower, passing the vaporizedportion of the oil in a continuous path counter-current to and incontact with reflux oil in the tower, collecting reflux oil in the towerabove the point of introduction of oil thereinto in thapath of flow oithe vapors but out of contact therewith, subjecting the collected refluxto contact with steam, and separately withdrawing the steamed reflux andunvaporized portion of the oil from the tower.

Signed at New York city, in the county of New York, and State of NewYork, this 6th day of April, A. 1D. 1927.

J OHN PRImOSE. Y

reflux oil in the tower above the point of

